Re: [PATCH] fault-inject: fix wrong should_fail() decision in task context
From: Lu Fengqi
Date: Wed Aug 02 2017 - 00:16:01 EST
On Wed, Aug 02, 2017 at 09:28:20AM +0900, Akinobu Mita wrote:
>Commit 1203c8e6fb0a ("fault-inject: simplify access check for fail-nth")
>unintentionally broke a conditional statement in should_fail(). Any faults
>are not injected in the task context by the change when the systematic
>fault injection is not used.
>
>This change restores to the previous correct behaviour.
>
>Fixes: 1203c8e6fb0a ("fault-inject: simplify access check for fail-nth")
>Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
>Cc: Lu Fengqi <lufq.fnst@xxxxxxxxxxxxxx>
>Reported-by: Lu Fengqi <lufq.fnst@xxxxxxxxxxxxxx>
>Signed-off-by: Akinobu Mita <akinobu.mita@xxxxxxxxx>
>---
> lib/fault-inject.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
>diff --git a/lib/fault-inject.c b/lib/fault-inject.c
>index 7d315fd..cf7b129 100644
>--- a/lib/fault-inject.c
>+++ b/lib/fault-inject.c
>@@ -110,10 +110,12 @@ bool should_fail(struct fault_attr *attr, ssize_t size)
> if (in_task()) {
> unsigned int fail_nth = READ_ONCE(current->fail_nth);
>
>- if (fail_nth && !WRITE_ONCE(current->fail_nth, fail_nth - 1))
>- goto fail;
>+ if (fail_nth) {
>+ if (!WRITE_ONCE(current->fail_nth, fail_nth - 1))
>+ goto fail;
>
>- return false;
>+ return false;
>+ }
> }
>
> /* No need to check any other properties if the probability is 0 */
>--
>2.7.4
>
>
>
With this fix, I can produce the IO ERROR by the fail_make_request.
--
Thanks,
Lu